Referring to FIG. 1 to FIG. 3, the structure of the conventional first kind and second kind of windshield wiper comprises a master wiper 2, in which having a first holding arm 4 being jointed with each articulation 3 on both ends respectively. And, a second holding arm 6 is jointed on the articulation 5 of each inwards end of said both first holding arm 4 respectively. A clamping device 7 is disposed on each outwards end of said both first holding arm 4 and both ends of said both second holding arm 6 respectively. A strip scraper 8 being made of flexible elastic material is clipped by means of these said clamping devices 7. And, a metal elastic stripe 801 (as shown in FIG. 3) is imbedded in order to brace the holding uphold on both sides of said strip scraper 8. Furthermore, on the joint of both ends of said strip scraper 8 and the outwards end of said both first holding arm 4 is securely sleeved by an end ferrule cap 9 respectively as shown in FIG. 1.
When said strip scraper 8 of both aforementioned conventional windshield wiper sweeps back and forth on the windshield G, a gap is created in said articulations 3, which being the joint of said master wiper arm 2 and said both first holding arms 4, and said articulations 5, which being the joint of each inwards end of said both first holding arms 4 and said both second holding arms 6. And, the more frequency by the wiper sweeps, the more gradually enlarged the gap will be. Hence, the linearity among said master wiper arm 2, said first holding arms 4 and said second holding arms 6 eventually loses alignment (as shown in FIG. 4). Consequently, said strip scraper 8 being bent indirectly is disabled to synchronously sweep in linear alignment and losing the effect of clearing off the extraneous impurities or dust. Thus, the turnover of replacing new product is increased. Furthermore, the way of replacement must be whole integral wiper instead of part by part individually. And, the discarded old products become garbage and pollute the environment.
Therefore, the businessmen bring the third kind of conventional windshield wiper (also called no-holding-arm wiper) into the market recently. As shown in FIG. 5 to FIG. 9, the wiper comprises a truss saddle 10, a stripe main body 20, a pair of bow elastic stripes 22, and two end ferrule caps 23. Wherein said stripe main body 20 is firmly clipped by said truss saddle 10 and is unitary-molded made of flexible elastic material. There are multiple strip fluted grooves 21 being formed on both sides of said stripe main body 20 with a unitary-molded (scraper edge 24 at its undermost side). And, said pair of bow elastic stripes 22 are made of metal and will be inserted into the uppermost pair of said strip fluted grooves 21 to serve as splint. Furthermore, on the joint of both ends of said stripe main body 20 and the both ends of said both pair of bow elastic stripes 22 is securely sleeved by an end ferrule caps 23 respectively.
Referring to FIG. 7 to FIG. 9, when said third conventional windshield wiper sweeps back and forth on the windshield G in tight pressure contact, said truss saddle 10 becomes the prime force-acting point (as shown in FIG. 8). Thus, the scraping pressure of the said wiper on said windshield G gradually increases lengthwise from said central truss saddle 10 toward both ends (as shown of black arrow in FIG. 8). Hence, the pressure of every contact point in said scraper edge 24 is not even distributed uniformly and not tightly contact with said windshield G. Consequently, the scraping effect of said wiper is diminished. Either, the noise due to the friction with said windshield G increases to affect the internal tranquility in the car contrarily.
Besides, said scraper edge 24, which being unitary-molded made of flexible elastic material, is splinted with said metal bow elastic stripes 22 on its both sides to bend itself. When said wiper sweeps back and forth, said both bow elastic stripes 22 bear different push and pull forces everywhere due to exchange of along or against motion direction. So that said whole wiper is tilted and bent distorted in consequence of action of squeeze and extract on said strip fluted groove 21 (as shown in FIG. 9). Contrarily, it decreases the lifetime of said stripe main body 20 without practicality. Moreover, said end ferrule caps 23 is to sleeve and buckle the snap-on notch 221 on both ends of said both bow elastic stripes 22. It can be easily fallen off unexpectedly in consequence of being deformed in aforementioned motion. Consequently, the separation of said bow elastic stripes 22 from said stripe main body 20 will happen to disable said wiper function in uselessness.
Accordingly, some other business men introduces the fourth kind of no-holding-arm wiper as shown in FIGS. 10, 10-A, 10-B, 11 and 11-A, and 12-A to 12-E, which comprises:
a truss saddle 30;
a bow elastic stripe 40, which being made by metal bow stripe, is securely jointed with the base side of said truss saddle 30 at its central upper side; On its surface, some square holes 41 are evenly punched; Near its both ends, a snap-on hole 42 is created respectively;
two stripe main body 50, which being unitary-molded made of flexible elastic material, is securely caught on said bow elastic stripe 40 at both sides of said truss saddle 30; At two sides of its bottom, a indented grapple stripe 51 is created correspondingly; At the internal top center of said indented grapple stripe 51, a cone-shaped suspending bracket stripe 52 is built
some detachable clamping devices 60 are securely buckled in each said square hole 41 respectively on said bow elastic stripe 40; On its upper section, a pair of protruding lugs 61 are created in cross sectional shape of trapezoid; On the center in each of said both protruding lug 61, a elastic barb 62 is created; On its lower section, a pair of jaw-like paws 63 is built;
two end ferrule caps 70 securely sleeves and buckles in each said snap-on hole 42 on both ends of said bow elastic stripe 40; On the center of its bottom, a spline buckle plate 71 is built internally; At each free end of said spline buckle plate 71, a snap-on lug 72 is created to be buckled in said snap-on hole 42 (as shown in the sectional view taken along the direction indicated by a line B—B as shown in FIG. 10.); And
a strip scraper 80 is unitary-molded made of flexible elastic material; On its upper section, a pair of strip fluted grooves 81 are created at its both sides in order to be securely caught and inserted by said jaw-like paw 63 of said detachable clamping device 60; Between said strip fluted groove 81 and its top side, a pair of metal elastic stripes 82 is mounted at both sides; A pair of elastic splint rods 84 are inserted into said strip fluted grooves 81 respectively; On its lower section, a scraper edge 83.
Said fourth kind of conventional windshield wiper is contrived by combining said conventional first kind, second kind and third kind of windshield wipers. Its advantage in replacing wiper is need to replace worn strip scraper 80 only instead of replacing whole integral wiper while said conventional first kind, second kind and third kind of windshield wipers have to replace whole integral wiper if any part being worn. In comparing one another, said fourth kind of conventional windshield wiper possesses advantages in expanses of environmental protection and replacing new product by consumers. It is also better in serving lifetime and scraping effect. However, it still exists some drawbacks as below.    1. Referring to FIGS. 11 and 11-A, just like said third conventional windshield wiper, said truss saddle 30 serves as force-acting point in the pressing contact of bow elastic stripe 40 with windshield G. So that the pressure in both end points of said strip scraper 80, which being at the bottom side of said bow elastic strip 40 is strongest compared with every other point. Thus, neither the scraping effect can be maintained nor the internal car tranquility can be sustained due to noise of friction with windshield G in consequence of every point not possessing even pressure distribution and closed tight contact with the surface of said windshield G.    2. Referring to FIG. 12, sections A to E, and FIGS. 10 and 10-A, the process steps of assembly are illustrated as below:
a. One by one, insert and buckle said protruding lug 61 of said detachable clamping device 60 into said square hole 41 of said bow elastic stripe 40 (as shown in the section A of the FIG. 12).
b. Push said detachable clamping device 60 from the bottom of said jaw-like paw 63 such that said elastic barb 62 being pressed and bent inwards (as shown in the section B of the FIG. 12). Continue to push it up to said elastic barb 62 passing through said square hole 41 and bouncing to its original status as well as being buckled in said square hole 41 (as shown in the section C of the FIG. 12).
c. Guide and sleeve said two stripe main bodies 50 into bow elastic stripe 40. During this process, careful to keep said indented grapple stripes 51 and suspending bracket stripe 52 dovetail with both side of said bow elastic stripe 40. And, to slide and sleeve them into said protruding lugs 61 of said detachable clamping device 60 (as shown in the section D of the FIG. 12).
d. After said two stripe main bodies 50 have been wholly sleeved with said bow elastic stripe 40, put and buckle said end ferrule cap 70 at both ends of said bow elastic stripe 40. So that said snap-on lugs 72 at the bottom side of said end ferrule cap 70 are completely inserted and buckled into said snap-on holes 42 of said bow elastic stripe 40 (as shown in the section E of the FIG. 12).
e. Finally, put and insert said strip scraper 80 into said jaw-like paw 63, which being the lower section of said detachable clamping device 60. And, put and insert said two elastic splint rods 84 into said strip scraper 80. All assembly process finishes here (as shown in the section F of the FIG. 12).
It is learnt from the above assembly process that the two stripe main bodies 50 must carefully with directionality in assembly and avoid to caused an error place by an incorrect direction. Therefore, the man-hour in assembly of the main bodies 50 is much more due to directionality in step c.    3. Referring to the section E of the FIG. 12 and the sectional view taken alone a line 10-A—10-A of the FIG. 10, said suspending bracket stripe 52, which being downwards formed in the internal top center of said stripe main bodies 50, is to serve as stopper. Its function is to block said elastic barb 62, which being in said protruding lug 61 of said detachable clamping device 60, from bending inwards. Thus, it prevents said stripe main bodies 50 from dropping off from said square hole 41 of said bow elastic stripe 40. Hence, its material should be non-elastic hard material instead of same flexible elastic material as that used by said stripe main bodies 50. Therefore, it not only causes extra expense in extruding process of mold but also increases the difficulty in production process, which also relatively results in elevation of production cost.    4. Usually, the windshield wiper in the market should be passed by erosion-resistant weather test to make sure it can stand being battered by the wind and the rain in practical car-driving usage. All said detachable clamping devices 60 in said fourth kind of conventional windshield wiper are directly exposed without any weather-stripping protective design such that being easily beaten by different degree of the wind and the rain during practical car-driving usage. Hence, it causes the increase of damage rate in consequence of bad erosion-resistant capability. Thus, its service lifetime is indirectly decreased and resulting in drawback of need to replace it early.